PHILADELPHIA (AP) — The parents of a Marine whose body came back from Greece missing his heart amended their federal lawsuit Wednesday to add the Greek government and an Athens hospital as defendants.

Craig and Beverly LaLoup, of Coatesville, are also suing the U.S. Department of Defense over the remains of 21-year-old Sgt. Brian LaLoup.

The Defense Department doesn't comment on pending litigation. Messages were left with the Greek government and state-run Evangelismos General Hospital.

LaLoup, who was assigned to a security detail at the embassy, had told a colleague he was suicidal over a breakup. The parents believe a Marine supervisor knew about his mindset, but instead of getting help, took him out for drinks. Their lawsuit alleges their son was allowed to get a weapon from a storage area later that night, despite his mood and level of intoxication, and shot himself.

The U.S. government is generally immune from wrongful death lawsuits, so the family is seeking damages only over their emotional distress caused by the missing heart.

They say they learned about the missing organ only accidentally, weeks after they buried their son. They also say they eventually were given a heart that wasn't his.

"This is his heart. This is his soul. This is what made Brian who he is," Beverly LaLoup told The Associated Press this week.

LaLoup, who was buried with full military honors, had previously served in Afghanistan and South Africa.

He died on Aug. 12, 2012, at Evangelismos General Hospital, where an autopsy was conducted six days later. The heart was found to be missing during a second autopsy conducted by U.S. military officials on Aug. 22 after the body arrived in Dover, Del.

The family only learned about the missing heart on Sept. 17, two weeks after the funeral.

Christos Failadis, a spokesman at the Greek embassy in Washington, D.C., said the heart was kept for toxicology tests. He declined to answer questions about what happened to it or why the family later received a heart belonging to someone else.

Pathologists say organs are often removed during autopsies for testing, but they said it would be unusual to use the heart, rather than blood or other fluids, for toxicology tests.